Would you buy a used com. 21 inch mower?

I do not want to spend the $900 on a new 21 inch mower due to not using it very often and was thinking about looking around for a used machine. (Toro with the Kaw. or a Honda unit)I have a old Toro personal pace machine with the Brig. engine and it is going to die soon. Is buying used machines a bad practice or has it worked out for others on this site.